NHESS Natural Hazards and Earth System Sciences NHESS Nat. Hazards Earth Syst. Sci. 1684-9981 Copernicus Publications Göttingen, Germany 10.5194/nhess-12-97-2012 Efficient dam break flood simulation methods for developing a preliminary evacuation plan after the Wenchuan Earthquake Li Y. 1 2 Gong J. H. 1 2 Zhu J. 3 Ye L. 1 Song Y. Q. 4 Yue Y. J. 5 State Key Laboratory of Remote Sensing Science, Institute of Remote Sensing Applications, Chinese Academy of Sciences, Beijing 100101, China Zhejiang-CAS Application Center for Geoinformatics, ZheJiang 314100, China Southwest-jiaotong University, Chengdu 610031, China College of Urban and Environmental Science, Tianjin Normal University, Tianjin 300387, China Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100185, China 11 01 2012 12 1 97 106 Copyright: © 2012 Y. Li et al. 2012 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://nhess.copernicus.org/articles/12/97/2012/nhess-12-97-2012.html The full text article is available as a PDF file from https://nhess.copernicus.org/articles/12/97/2012/nhess-12-97-2012.pdf

The Xiaojiaqiao barrier lake, which was the second largest barrier lake formed by the Wenchuan Earthquake had seriously threatened the lives and property of the population downstream. The lake was finally dredged successfully on 7 June 2008. Because of the limited time available to conduct an inundation potential analysis and make an evacuation plan, barrier lake information extraction and real-time dam break flood simulation should be carried out quickly, integrating remote sensing and geographic information system (GIS) techniques with hydrologic/hydraulic analysis. In this paper, a technical framework and several key techniques for this real-time preliminary evacuation planning are introduced. An object-oriented method was used to extract hydrological information on the barrier lake from unmanned aerial vehicle (UAV) remote sensing images. The real-time flood routine was calculated by using shallow-water equations, which were solved by means of a finite volume scheme on multiblock structured grids. The results of the hydraulic computations are visualized and analyzed in a 3-D geographic information system for inundation potential analysis, and an emergency response plan is made. The results show that if either a full-break or a half-break situation had occurred for the Chapinghe barrier lake on 19 May 2008, then the Xiaoba Town region and the Sangzao Town region would have been affected, but the downstream towns would have been less influenced. Preliminary evacuation plans under different dam break situations can be effectively made using these methods.

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